The prior art knows multiple embodiments of so-called roller spindles with ballscrew or planetary roller arrangements. Small pitches are impossible to realize using ballscrew systems as disclosed and specified for example in DT 2,715,762, DE 2,750,054, DE 2,810,001, DT 2,715,761, or DT 2,051,413, because the precision manufacture of balls with a diameter of 0.5 mm or less at reasonable cost is virtually impossible. Furthermore, given the absolute necessity of a ball guide, there are problems with smooth running and ball wear.
Planetary roller spindles, as disclosed and specified for example in DT 2,065,442 and DE 2,838,329, operate with various embodiments of the spindle, roller, and nut components. For example, threads or grooves may be machined on the components. Basically, however, the contours of the rollers engage the contours of both the spindle and nut in order to produce an axial flow of force. Therefore, compatible grooves or threads must be provided on all three components.
In order to prevent or compensate axial wandering of the rollers, so-called stop-motion or resetting devices such as are disclosed and specified in DE 2,320,406, DE 2,823,729, and DT 2,150,739, or toothed rings as presented and described in DT 2,601,493, are provided for forced driving of the rollers.
Likewise, both nuts and rollers can be provided with grooves only, so that the rollers can execute no axial motion, while the spindle is embodied with a multiple thread whose number of threads matches or is a multiple of the number of rollers, as described for example in DE 2,807,952.
In this manner, it is simple to produce roller spindles of higher pitch. However, for roller spindles with a very small pitch, smaller than 0.3 mm/turn, having a useful number of rollers which is more than three, it is necessary to make such fine thread profiles that it is hardly possible to manufacture them in any reasonably economical manner.
Furthermore, DT 2,059,528, DT 2,715,203, and DT 2,721,977 present and specify transmissions, some of which even permit shifting, and which are comprised of the basic components in the roller spindle designs cited above.
In order to translate a rotary motion into an axial motion, various arrangements are devised, often even provided with obliquely disposed ball bearings, as disclosed and specified for example in DE 2,026,550, DT 1,750,637, DE 2,709,006, and DE 3,219,972.
However, the demand for a spindle system with very small pitch, continually reiterated for example in robotics applications, either cannot be met at all by the numerous designs described in many publications, or only at exaggerated expense, or with sacrifices in precision, running smoothness, and service life.